A variety of soil release compositions for fabric conditioning or fabric softener compositions have been introduced and are known in the art. The soil release compositions often contain polymers such as amphiphilic compounds based on a polyester backbone. These backbones can be copolymers of ethylene glycol and terephthalic acids or polyethylene terephthalate and polyethylene glycol polyester polyether. These polymers consist of hydrophilic and hydrophobic units and are analogous to synthetic fibers such as those found in polyester fabrics which contain terephthalate, ethyleneoxy or propyleneoxy polymeric units. The similarity in chemical structure of soil release polymers and polyester synthetic fabrics allow for binding or deposition of soil release polymers onto fibers and modify surface energy by imparting hydrophilic characteristics to fiber. This results in better cleaning by either retarding the attachment of oily soil to fibers and thus minimizes subsequent soiling or improving the wetting of fibers and susceptibility of a fabric to detergent during washing and thus, to facilitate soil removal. The benefits of these types of soil release polymers are limited to certain synthetic polyesters.
For different fabrics such as cotton or nylon, the difference in chemical composition and fabric properties requires different mechanisms for soil removal. Cotton is considered as a hydrophilic fabric. It contains hydroxyl end-groups which tend to fix stain and soil easier than polyester or other synthetic fabrics. Nylons are made of fiber of polyamides with terminal amino and carboxyl end groups.
There still is a need for compositions that can be incorporated during general washing or conditioning cycle and that protect fabrics from soil and enhance the removal of soil.